1. Field of the Invention
The present invention relates to a television signal generator for highlighting a portion inside or a portion around a pattern image such as a character, numeral or symbol.
2. Description of the Prior Art
In order to highlight a portion around a pattern image such as a character, numeral or symbol, a manual operation of writing a highlighting pattern on the original film has been conventionally required.
It is an object of the present invention to provide a circuit means for electrically highlighting a portion around a pattern image.
A circuit is proposed in U.S. Ser. No. 622,134 by the same inventor as a simple means for electrically highlighting a portion around a pattern image. This circuit slightly delays an original pattern signal in the horizontal and vertical directions to obtain a plurality of delayed signals. A pattern of a larger area than the original pattern image is obtained by logically ORing the delayed signals. This process is repeated so as to form a profile pattern to surround the original pattern image. The brightness of the profile pattern is instantaneously decreased/increased to highlight it.
However, when highlighting is performed over the entire surface of the screen with such a circuit means, hardware becomes large in size, resulting in an impractical circuit.
It may be proposed to enlarge a graphic pattern by numeral operation using an image memory and a computer and to highlight it by increasing the brightness of the enlarged portion. However, in order to form a highlight pattern which is enlarged first and then reduced as time elapses, a very large number of operation steps is required, and processing cannot be performed in a short period of time substantially corresponding to real time.